Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
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Chapter 3, Problem 20SQ
To determine
Choose the best option that represents the consideration of number of magnetic starter poles.
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20.a. A capacitive sensor is used to detect the presence of _______ objects.A. ferrousB. nonmovingC. nonconductiveD. magnetic20.b. A three-phase motor can be made to run backwards byA. connecting a resistor in series with the armature.B. reversing the control voltage connections.C. reversing three of its power leads.D. reversing two of its power leads.
Chapter 3 Solutions
Electric Motor Control
Ch. 3 - Prob. 1SQCh. 3 - How many poles are required on motor starters for...Ch. 3 - If a motor starter is installed according to...Ch. 3 - Using the time limit overload or the dashpot...Ch. 3 - What causes the AC hum or chatter in AC...Ch. 3 - What is the phase relationship between the flux in...Ch. 3 - In what AC and DC devices is the principle of the...Ch. 3 - What does the electrician look for to remedy the...Ch. 3 - What type of protective enclosure is most commonly...Ch. 3 - What advantage is there in using combination...
Ch. 3 - What safety feature does the combination starter...Ch. 3 - Prob. 12SQCh. 3 - How is the size of the overload heaters selected...Ch. 3 - What type of motor starter enclosure (include NEMA...Ch. 3 - Prob. 15SQCh. 3 - Prob. 16SQCh. 3 - Prob. 17SQCh. 3 - Prob. 18SQCh. 3 - Select the best answer for each of the following....Ch. 3 - Prob. 20SQCh. 3 - Prob. 21SQCh. 3 - Select the best answer for each of the following....Ch. 3 - Prob. 23SQCh. 3 - Select the best answer for each of the following....Ch. 3 - Select the best answer for each of the following....Ch. 3 - Select the best answer for each of the following....Ch. 3 - Select the best answer for each of the following....Ch. 3 - Prob. 28SQCh. 3 - Select the best answer for each of the following....Ch. 3 - Prob. 30SQCh. 3 - Prob. 31SQCh. 3 - What is the difference between a grounded control...Ch. 3 - A control transformer has a primary voltage of 480...
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- Subject: Power Engineering.arrow_forwardPlease answer alll with brief explanationarrow_forward6.a. Arcing in manual starters is eliminated by the use ofA. overload relays.B. nonconductive contacts.C. blowout coils.D. spring-loaded handles.6.b. Chattering of AC contactors is prevented byA. blowout coils.B. air gaps.C. secondary windings.D. shading poles.arrow_forward
- 9.a. The major failure area of a typical wound-field and wound-armature DC motor isA. a faulty commutator segment.B. open field windings.C. brush wear and failure.D. bearing failure.9.b. The magnetic material that's placed inside a coil of wire in a motor is called aA. concentrator.B. pole.C. form.D. rod.arrow_forward1. It is a machine that converts mechanical energy to electrical energy. 2. It is a machine that converts electrical energy to mechanical energy. 3. It is cylindrical or drum-shaped where the coils are placed and can either be lap wounded or wave wounded. 4. It connects the commutator to the other parts of the DC machine. 5. It serves as the housing of the dc machine. 6. True or False: The shunt field winding is part of the armature. 7. True or False: The long shunt compound generator is when the armature is in series with the series field winding and parallel to the shunt field winding. 8-10. Your newly built house needs an elevator. Which from the following will be best to use- series, shunt or compound motor and why?arrow_forwardIdentify the DC Generator used for Arc Welding purpose. With a neat sketch explain its working. List it's advantages and disadvantages.arrow_forward
- 14.a. An encoder is a device that is used toA. excite the motor's interpoles.B. feed pack position information.C. reduce brush sparking.D. commutate the field windings.14.b. The letters CEMF are used to describeA. centrifugal forces within a motor.B. the portion of the supplied current that is converted to heat.C. countervoltages and currents created within a motor.D. critical winding currents that should not be exceeded.arrow_forwardList the probable causes if the armature dos notable release after the magnetic starter is de - energized .arrow_forwardWhile discussing armature testing: Technician A says to test for shorts, place the ohmmeter leads on a commutator segment and armature shaft. Technician B says that continuity should exist between the commutator and the armature shaft. Who is correct?arrow_forward
- The preferred method for applying the field excitation voltage uses a field relay which operates on the principle of A. speed application. B. time application.C. angle application. D. thermal application.arrow_forwardExplain how DOL magnetic starter works step by step with diagram and pictures.arrow_forward6.a. When you're taking a PM motor apart you should exercise special care not to damage theA. end bells.B. commutator.C. permanent magnets.D. brush holders.6.b. A PM field servo motor may be equipped with a resolver that is used toA. excite the armature windings.B. create a voltage that increases with velocity.C. prevent the brushes from sparking.D. feed back position information.arrow_forward
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